#124 Power Transformer?

[michaelwwesbrook]

I’m about to purchase transformers for my up coming #124 build. I’m seeing PT’s that are said to be for Twin’s but have pretty different spec’ed voltages so I’m wondering what’s best?

https://reverb.com/item/56131932-pacifi ... t=56131932

This one from Pacific is said to be 315v with no load where as the Mojotone is listed at 340v. I’m leaning towards going with the Pacific as their reputation seems to be great but is the spec ideal?

Please forgive my ignorance on the subject, I’m learning as I go!

[dorrisant]

My experience with Pacific is nothing but great. 340-0-340 seems like an unloaded voltage measurement... 314-0-314 seems a loaded measurement. I could be wrong, but I think that these are both hitting the same targets although their reporting is more apples to oranges. I have used PTs from both manufacturers and had no issues with the loaded voltages not being very close to what was claimed.

Mercury Magnetics has been spot on every time I've used them... Just sayin'.

Also, good luck on the #124. I love that circuit and most do as well.

[galtjunk]

Heyboer has great power transformers and they are reasonably priced.
Call or email them.
Heyboertranformers.com
Their website sucks but their transformers are great.

Standard Twin Reverb: HY022756 HTS-7157 VC 9961700

Black Face Plus (wound for #183 with EL-34 and relay taps) HTS-10359 9961409

This one will handle 6l6 or el-34 and it has a second 6.3v tap for the relays.
This is the one I always use.

[Stephen1966]

I like the Pacifics, as well, but I hear they can sound a bit stiff compared to those, for instance, by Chris Merren http://www.merrenaudio.com/. I'm actually using a Hammond 290FEX so I can't offer you any pearls of wisdom here (nothing in my experience to compare it to) but as far as hearsay goes, it gives you some choices.

My 124 derived circuit has ten tubes altogether. I like the Pacific because it is rated for a 6A heater supply. AC hum (60Hz or 50Hz) becomes more an issue the more current you draw and the overhead in the Pacific's filament winding suggests on paper at least, that it will run cooler - and more importantly, quieter. Especially if you are building a more conventional 124 with 7 tubes.

Good luck, have a look at the Pacific's website though https://pacificaudiomagnetics.com/ you might get a better deal if you get it from them, there.

Stephen

[Lothy]

I used a Hammond 290FEX (FX for 120VAC). Works perfect for me. But I wish it has a 12V winding for the relais power. If there is a next time, I would use this one instead:

https://www.tube-town.net/ttstore/tt-du ... ormer.html

It can provide more heater current and has the desired 0-6-12 V winding for the relais and, in my case, to provide a 9V dc outlet for an external reverb pedal.
On the primary side it will fit for 120V as well and there is a 50w version too.

Cheers
Gerhard

[Stephen1966]

I used a Hammond 290FEX (FX for 120VAC). Works perfect for me. But I wish it has a 12V winding for the relais power. If there is a next time, I would use this one instead:

https://www.tube-town.net/ttstore/tt-du ... ormer.html

It can provide more heater current and has the desired 0-6-12 V winding for the relais and, in my case, to provide a 9V dc outlet for an external reverb pedal.
On the primary side it will fit for 120V as well and there is a 50w version too.

Cheers
Gerhard

Great find! Can't believe I hadn't seen that one. I don't have any problems with the Hammond either. My basic incompetence with heater wiring was the culprit for any hum I experienced. Now I've sorted that out, it's as quiet as a church mouse. So we can push the Hammonds to their limit - they are very robust. This Tube Town TX is interesting though. Can see the utility of having a relay supply taken off it, instead of having a separate TX for the relays. That supply might also be used to drive a fan. You can cook eggs on it when a quartet of 6L6s start singing

The guy who knows stuff at Tube Town seems to be on holiday. Tell me Gerhard, do you think the stated 1.5A rating is for both 6V and 12V supplies? The label on the TX in the photo, in the datasheet, says 'sec 4: 0V-6V-12V @ 1A...'

Anyway, I'll ask them when they get back off holiday. In the meantime, first thing I did when looking for a PT was look for the specs on the Fender 022756 [Edit: which IIRC was produced by Schumacher]

ODS_124023.jpg

Fender's export version being the 022764 (according to TAD's site: https://www.tubeampdoctor.com/en/mainst ... assman-100. Over at EL34World's site we have some specs for the 022756 for a primary of 120V: https://el34world.com/Transformers/fentrans.htm. Again, it has a healthy 6A on tap for the heaters though the secondary is only rated for 310mA. So historically, the 124 was asking a lot from the HT secondaries of this transformer. That might be a clue to its legendary tone. Point is though, almost any modern equivalent is going to offer around 500mA on the HT secondaries and that's plenty - even on a monster like mine.

So @michaelwwesbrook, you might proceed by looking at your circuit requirements and working backwards from that. You have a lot of options open to you, especially if you are in the States, for example, here's another: https://www.tedweber.com/w022756/. Most, if not all of these will work but perhaps someone with more experience than me can chime in with any insight into how these different TXs sound?

Thanks again Gerhard and good luck Michael.

Stephen

[Lothy]

Tell me Gerhard, do you think the stated 1.5A rating is for both 6V and 12V supplies? The label on the TX in the photo, in the datasheet, says 'sec 4: 0V-6V-12V @ 1A...'

From what I suspect from the datasheet, it should provide 1,5A @ 6 and 12 V.
In case of heater supply, a Twin has 3 more preamp tubes than an ODS. The 290FEX provide 5,5A which gives you 100mA spare on a Twin. Leo was a penny pincher, just enough is good enough.
For a standard ODS with 4 x 6L6 and 3 x ECC83 (lets use this term, just for fun), you have plenty of spare current.

Cheers
Gerhard

[TimDude]

...Mercury Magnetics has been spot on every time I've used them... Just sayin'...

I'm looking into kicking off a #0124 ODS build too, but I'm not sure which OT to buy. Which model Mercury Magnetics transformers do you typically order?

For the PT, I was thinking of just going for the FBFTP. If I should consider something else, please feel free to let me know.
For the OT, I'm a bit lost. They have several 100 watt OTs: FBFTO-100, FBFTO-100M (advertised as a "smaller stack"), FBFTO-100X, FBFTO-100-UL
For 85 watt OT's they have: FBFTO-85 (4Ω), FBFTO-85M (4 & 8Ω), FBFTO-85MT (4, 8 & 16Ω), FBFTO-85-FS (4Ω).

Should I spring for the 100 watt OT? Is it necessary? I'm looking to expand headroom if that's worth anything, although I know these amps are already known for their headroom.

True to their reputation, Mercury Magnetics is lacking nearly all documentation. Do their transformers come with documentation in the package they ship with? I don't want to be stuck guessing which wires are which.

[Colossal]

True to their reputation, Mercury Magnetics is lacking nearly all documentation. Do their transformers come with documentation in the package they ship with? I don't want to be stuck guessing which wires are which.

Yes, they come with a wiring diagram. Before you buy or if you have questions, all you need do is email them and they will send you a sheet on any transformer in the catalog.

[ijedouglas]

I'm looking into kicking off a #0124 ODS build too, but I'm not sure which OT to buy. Which model Mercury Magnetics transformers do you typically order?

I would seriously reconsider MM transformers. I have a cupboard full of them... I find them stiff and hard. I have tried just about all of the other brands as well (all in the cupboard ) ... if you want to get close, find vintage schumachers. I was lucky and found a twin carcass for parts... PT/OT/choke for $300

[WhopperPlate]

Pacific transformers are my favorite for twin iron…I like the clarity they have . Imo ,compared to classic tone those are muddy and dark to my ears.

Though in my humble opinion nothing beats Merren, but I have always been biased toward Marshall … I would love to have him wind twin transformers.

I have used Hammond power with pacific output with great results . I feel like they are generally looser feeling than pacific power I have compared in similar circuits. Pacific power feels nice and stout, but the ones I have used ate custom and aren’t the pacific stock numbers . Nowadays they are emphasizing cloning vintage transformers precisely , warts and all , so generally less than the listed handling specs are common. I think I read 375ma current rating for the ht secondaries, instead of say 450ma or 500ma. I think I remember the output transformers measure 2.2k- 2.4k …I have had mine wound with the common industry ratings .

I do have a stock twin set from pacific that I am going to utilize and compare against the rest. That will be fun and revealing

[TimDude]

I would seriously reconsider MM transformers. I have a cupboard full of them... I find them stiff and hard. I have tried just about all of the other brands as well (all in the cupboard ) ... if you want to get close, find vintage schumachers. I was lucky and found a twin carcass for parts... PT/OT/choke for $300

Interesting. It's not my intention to dismiss your experience, I believe you! But part of me just wants to go new. I was also looking at Hammond Hammond 290FX for my PT and a Hammond 1760W for my OT. Although, WhopperPlate is talking up the Pacific OT. Maybe I'll look into that. I appreciate your response. I have read elsewhere people's critique of MM being "stiff" and "hard".

Pacific transformers are my favorite for twin iron…I like the clarity they have . Imo ,compared to classic tone those are muddy and dark to my ears.

Maybe I consider this OT more, Pacific's "Fender Dual Showman Reverb Output Transformer."
Link to spec sheet here: https://cdn.shopify.com/s/files/1/0519/ ... 1660329511
WhopperPlate, have you tried the Hammond 1750W or 1760W in the OT position before? If so, what did you think? I think I would be perfectly fine getting a Hammond PT such as the 290FX like you suggested. Amplified Parts sells their stuff for great prices. Although, I suppose I could also go for Pacific's "Fender Dual Showman Reverb Power Transformer" and get a complete package from them too. When you mention having a "stock set," are those the two transformers you are talking about? I appreciate your input.

[WhopperPlate]

Yeh, stock set is referring to what they sell listed in the website . Keep in mind the OT is only rated for 4 ohm speaker output, so if you need multiple taps right now they won’t do it without charging extra custom fees . Apparently they are going to have this be a standard feature in the future for the modern line, or whatever .

About MM: great sounding , amazing , harmonics swirling, but they are their own thing . For easy reference I will say they aren’t vintage sounding , yes tight and stuff if you aren’t careful in many circuits. That’s just my experience, which doesn’t include a 124 with MM

[michaelwwesbrook]

I just ordered the OT from mojo and am leaning towards the Hammond for the PT. I got a quote from Pacific for a 4/8/16 OT and it was a 5 week lead time priced just over $190. The Mojo (Heyboer) seem to be well loved here as well and will be delivered next week.

Generally I’m not looking for stiff and tight (although I know much of it is inherent in the design) so any OT/PT choice I can make to lean the other way might be best for me.